\\[-1.8ex] Soil Heterogeneity & $-$0.621$^{***}$ & $-$0.489$^{***}$ & $-$0.478$^{***}$ & $-$0.475$^{***}$ & $-$0.471$^{***}$ & $-$0.471$^{***}$ & $-$0.471$^{***}$ \\ 
  & (0.163) & (0.138) & (0.135) & (0.133) & (0.132) & (0.131) & (0.132) \\ 
\\[-1.8ex] 
Observations & 13,726 & 13,726 & 13,726 & 13,726 & 13,726 & 13,726 & 13,726 \\ 
R$^{2}$ & 0.387 & 0.408 & 0.409 & 0.411 & 0.412 & 0.412 & 0.412 \\ 
